In making a metal framing connection between metal channels as described and illustrated in U.S. Pat. Nos. 2,345,650 and 2,696,139 to Attwood, one inserts a channel type nut having a spring attached into the continuous slot of one of the channels. The channel nut is turned 90.degree. clockwise to position the parallel grooves in the nut with the inturned flange edges of the channel. The spring on the back of the nut holds the nut against the flange edges until the connection is complete. A fitting is positioned over the nut and a bolt is inserted through the fitting and threaded into the nut and tightened to the required torque to complete the connection of the fitting to the channel. The same procedure is used to connect the other channel to complete the connection between the two channels.
The disadvantages of the above procedure using the fasteners described are as follows:
1. The simplest of connections between two channels consists of 5 separate parts, a fitting, 2 nuts and 2 bolts. More complex connections require even more parts.
2. Nuts using a support spring to push against the inside back of the channel to hold it in place until a bolt is threaded into place require different length springs to accommodate different depths of channels. In addition, the channels cannot accommodate a run of wire or pipe within the channel when nuts having support springs attached are used.
3. Small parts, i.e., nuts and bolts, may easily be dropped or misplaced during assembly.
4. When the bolt is inserted through the fitting, the nut can be tipped and dislodged. In a vertical channel arrangement it could fall out of the channel.